Machining for port work

[Deets066]

I would like to start a thread for the machining end for porting. Add whatever you think is relevant, from clamping jugs, tips for indicating, fixtures, or what tooling you guys are
Useing.

We recently acquired a mill in our shop.

 

[Deets066]

Here is a 660 jug in an independent 4 jaw chuck. I also have a rotary table to attach the chuck to. What would be the easiest way to clamp the jug? Right now the grooves in the jaws lock into the fins making it unable to level up.

I've been thinking of making a universal plate to set jugs on with slots to bolt the jug to. In order to do the base and squish at the same time I thought about tapping the mounting holes in the base so I wouldn't have anything stickin out past the base. Thoughts?

 

[huskihl]

View attachment 12983

Here is a 660 jug in an independent 4 jaw chuck. I also have a rotary table to attach the chuck to. What would be the easiest way to clamp the jug? Right now the grooves in the jaws lock into the fins making it unable to level up.

I've been thinking of making a universal plate to set jugs on with slots to bolt the jug to. In order to do the base and squish at the same time I thought about tapping the mounting holes in the base so I wouldn't have anything stickin out past the base. Thoughts?

I've always seen a plate like you're talking about bolted to the jug. Cut squish. Put a mandrel in the bore, Chuck up the mandrel, and cut base. Too much flex to mount directly to the fins. And I don't think I could trust threading into 1/4" of aluminum. But yea, I see your point. Once and done would be nice

 

[Deets066]

I've always seen a plate like you're talking about bolted to the jug. Cut squish. Put a mandrel in the bore, Chuck up the mandrel, and cut base. Too much flex to mount directly to the fins. And I don't think I could trust threading into 1/4" of aluminum. But yea, I see your point. Once and done would be nice

They use mandrels for cutting based on a lathe, that wouldn't work to well in an end mill

 

[Deets066]

Oh... And the fins won't flex, they just break

 

[drf256]

Deets, it's like every other shortcut. It's probably not gonna work.

You gotta make a square plate like Randy does, drill holes, thread holes, bolt jug up with some type of spacer above the top that will allow the jug to move by adjustment of the bolts.

Center it with the 4 jaws and then square it with the bolts. Rinse and repeat till it's right.

You could conceivably cut 4 pieces of aluminum stock and place around jug so the teeth don't screw you up. I'd be worried about broken fins. I know a guy that can fix em for you though

 

[Moparmyway]

I have seen a few videos of guys clsmping jaws directly to the fins and getting squish cut along with the base in one chucking operation.

It gave me the hebbe-jebbe's , just waiting for the cylinder to pop out, but it held fine. I don't have the bowls to try it, so I made a plate for each cylinder I've done. Have to have a test indicator and a few dial indicators to be sure of straightness and amount removed, but thats all on a lathe, I can only dream of having a mill

 

[Deets066]

Deets, it's like every other shortcut. It's probably not gonna work.

You gotta make a square plate like Randy does, drill holes, thread holes, bolt jug up with some type of spacer above the top that will allow the jug to move by adjustment of the bolts.

Center it with the 4 jaws and then square it with the bolts. Rinse and repeat till it's right.

You could conceivably cut 4 pieces of aluminum stock and place around jug so the teeth don't screw you up. I'd be worried about broken fins. I know a guy that can fix em for you though

I will probably make a plate, but if I just bolt it like Randy does then how do I cut my base? The base holes would need to be threaded so there were no nuts above the base.

I would feel fine clamping to the fins, the jug isn't going to spin fast like on a lathe, only as fast as I can turn the handle. When I had the jug clamped with just the jaws I could pick up the 8" chuck by lifting with the jug and had zero movement. It's just very hard to center and straighten at the same time when clamping directly to the fins

 

[drf256]

Then try it with some aluminum stock or oak between the Chuck teeth and jug.

So you're gonna use an end mill and rotate the jug?

I agree. The forces will be different.

 

[drf256]

You can also just make a fixture to fit your jugs, then clamp that into your rotary base.

 

[drf256]

I contemplated welding a piece of round stock to the top of the jug, turning that square, the flipping the jug over for machining.

Theoretically, it should square the band perfectly.

 

[Redfin]

What are the advantages of a mill/lathe compared with each other?

 

[Deets066]

I contemplated welding a piece of round stock to the top of the jug, turning that square, the flipping the jug over for machining.

Theoretically, it should square the band perfectly.

I've been thinkin the jug will sit much flatter if I surface the top of jug first, same thing kinda

 

[drf256]

Yes. But the cooling fins are most important there.

I've toyed with extending the cooling fins off of an 026 jug. Letting them bulge out the side more wherever I can.

I'm glad I left some fin on top of my 024/6 build. It was done out of pure laziness, but now I see an advantage to it.

 

[Deets066]

Then try it with some aluminum stock or oak between the Chuck teeth and jug.

I tried rubber, that didn't work. Fins are on an angle and the jug would "ride upward" when I tightened it. I might try wood

 

[drf256]

Wood's gonna have a memory for those fins.

 

[Warped5]

Just my $.02 here .... but I've never seen anyone on these boards do their machining on a mill. Not saying it can't be done, just that we've never seen it.

If you (care or want) to go to Another Site, search up some of Randy's old threads (I think some may have videos) on how he does his machining. IIRC, he has a bunch of mandrels set up in various diameters (made of thermonuclear nylon) to insert into the cyl and chuck up in his lathe. With these he cuts the base. To cut the squish, he has a jig set up to attach the cyl to the headstock and he does the cutting with a boring bar.

Good luck. I hope this thread keeps going ... love to read about this stuff.

 

[Deets066]

True but I wouldn't need to clamp it really tight until my runout was good. But yes I see issues with that method too

 

[Red97]

Get a Boring head.


Imo, endmill is not the way to cut the base. Unless you are using the rotary table. The lateral cuts across a base will leave (channels) for an air leak. Vs a radial groove when cut with a boring head/lathe.

If you are only doing low volume or the same jug, clamp it like in your pic and shim the table to align the jug. Looks like it will hold it just fine.

Seriously look into a boring head, cut base and squish in that one setup.

 

[Mattyo]

I cut the crankcase...instead of cutting cylinder base....and I do it on a Bridgeport